Electrical ship propulsion is not a new concept. Its history began at 1912, when the collier “Jupiter” installed with reciprocating engine and dc machines was built. Although many ships with electrical propulsion system known as T-2 tankers were built during World War II, only ships requiring excellent maneuverability, e. g. icebreaker and research vessel, adopt electrical propulsion system recently. This situation is caused by the disadvantages in volume, weight and cost of electrical propulsion, However, electrical propulsion has many advantages in addition to excellent maneuverability which fit in modernization of ship. Technologies in every fields are progressing always. It is meaningful, therefore, to reevaluate the ship propulsion system, taking ac count of new technologies and/or improved technologies. This paper gives historical reviews of electrical propulsion and modernization of ship at first. The features of several kinds of electrical propulsion and the problems encountered in adoption of superconducting machines are described. Some remarks are given about shipboard refrigeration system for superconducting machine. At last, the present status of researches and developments for superconducting ship propulsion, mainly in U.S.A., are reviewed.
Several organic insulators in superconducting magnets for fusion reactors are irradiated in a fission reactor at 5K and their mechanical properties are measured at liquid nitrogen temperature (77K). After irradiation with fast neutron fluence of 1.7×1017 nvt and γ dose of 4.5×108R, polypropylene is broken into pieces and polycarbonate and Mylar becomes too brittle to permit tensile test. Breaking stress and elongation of Nomex reduce as compared with that of unirradiated specimen. Kapton exhibits only a little decrease in breaking stress after irradiation of fast neutron fluence of 3.3×1017nvt and γ dose of 8.8×108R, and shows the most excellent properties against the irradiation.